# Holly finds that (11m - 13n + 6mn) - (10m - 7n + 3mn) = m - 20n + 9mn. What error did Holly make?

**Solution:**

Holy calculated (11m - 13n + 6mn) - (10m - 7n + 3mn) = m - 20n + 9mn.

The mistake Holly made is that he didn’t solve the brackets first. He only used the additive inverse of 10m when combining like terms.

The correct solution is (11m - 13n + 6mn) - (10m - 7n + 3mn) = m - 6n + 3mn

## Holly finds that (11m - 13n + 6mn) - (10m - 7n + 3mn) = m - 20n + 9mn. What error did Holly make?

**Summary:**

Holly didn’t use additive inverse for all the terms while combining like terms.

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